What Do Carbon Filters Remove From Water?

Carbon filters might seem simple, but there’s some cool chemistry behind how they improve your water quality. Carbon filters use a process called adsorption, not to be confused with absorption. Adsorption is when contaminants stick to the surface of the carbon, while absorption is when a substance is drawn in, like water soaking into a sponge. Because carbon has a porous structure, it offers tons of surface area for trapping unwanted substances like chlorine, odors, and certain chemicals. 

That means every drop of water gets scrubbed clean as it passes through, removing chemicals you can’t see but might otherwise taste or smell. Whether you’re filling a glass to drink or rinsing veggies at the sink, understanding how this process works helps you feel more confident about what you're putting in your body.

Not all carbon filters are created equal, though. There are a few different types, each with its own strengths:

• Granular Activated Carbon (GAC): GAC filters contain loose carbon granules that allow water to flow through quickly. They're great at improving taste and removing chlorine, but because of the shorter contact time, they might not be as effective at filtering out more stubborn contaminants.
• Powdered Activated Carbon (PAC): PAC is made of finely ground carbon powder and is typically used in combination with other filter types or media. Its fine texture means it can adsorb contaminants efficiently, though it’s usually part of a larger filtration system rather than a standalone filter.
• Catalytic Carbon: This is a specially treated form of activated carbon that targets harder-to-remove contaminants, like chloramines (a common chlorine alternative used in municipal water). Catalytic carbon is especially useful in areas where other carbon filters fall short.
• Carbon Block: Carbon block filters compress carbon powder into a solid block. This design forces water through a tighter structure, increasing contact time and filtration efficiency. As a result, carbon block filters can remove smaller particles and a wider range of contaminants while still improving taste and odor.

• Volatile Organic Compounds (VOCs): VOCs are chemicals released from solvents, gasoline, and industrial processes that can end up in groundwater. Carbon filters are highly effective at trapping many VOCs, thereby helping to protect against long-term exposure to these harmful compounds.
• PFAS and Pharmaceuticals: Some advanced carbon filters, particularly carbon block and catalytic carbon, can reduce certain PFAS (also known as “forever chemicals”) and trace pharmaceuticals that may be present in tap water. Not all carbon filters remove these, so it’s important to check performance data. PFAS compounds have been linked to a range of health concerns, including hormone disruption and immune system effects. 
• Pesticides and Herbicides: Runoff from farms and lawns can introduce pesticides and herbicides into the water supply. Carbon filtration is effective at reducing many of these chemicals, especially those that are organic in nature.
• Microplastics: Microplastics are tiny plastic particles that can make their way into drinking water. While carbon filters can help reduce them, especially when tightly packed like in carbon block filters, their effectiveness depends on the filter’s micron rating.
• Taste and Odor Impurities: One of the most noticeable improvements with carbon filters is the reduction of funky tastes and smells. By removing chlorine, sulfur compounds, and other organics, carbon filters help your water taste and smell better.